The present invention relates to a scroll-type compressor having movable and stationary scrolls and, in particular, to an improved lubrication arrangement and method for lubricating the components of a scroll-type compressor.
One type of scroll-type compressor to, which the present invention is applicable, has a compressed gas discharge port in the stationary scroll. Unexamined Japanese Patent Application No. 58-117380 discloses this type of compressor. The lubrication system of that compressor employs an oil sump at the bottom of a housing that accommodates an electric motor for driving the movable scroll. Oil in the oil sump is pumped by an oil pump through an oil passage that is eccentrically formed in the motor shaft (drive shaft of the movable scroll). The oil passage introduces the oil into a bearing located between the motor shaft and the movable scroll. Then, the oil in the bearing is radially introduced from the bearing to a thrust support member, which rotatably supports the movable scroll, and lubricates the support member. Finally, the oil is collected by a recovery hole and falls to the oil sump by gravity.
According to above application, it is necessary to install an oil pump in order to ensure a sufficient supply of oil to the sliding surfaces of the bearing. The requirement for an oil pump increases the cost of the compressor and introduces another component that may constitute a failure point. It therefore is desirable to achieve lubrication of the compressor without incorporating separate oil pump.
One object of the present invention, therefore, is to provide a scroll-type compressor and a method for lubricating the same, which obviates the need for an oil pump. Another object of the invention is to lubrication of a scroll compressor by introducing a refrigerant including a lubricant into the components to be lubricated through a pressure difference that exists between two or more regions of the compressor.
To achieve the foregoing, the present invention incorporates introducing passages for introducing lubricant-containing refrigerant from a compression chamber of a scroll-type compressor to a lower pressure region where the lubricant can lubricate components of the drive mechanism. At least part of the introducing passage is effective to restrict the rate of flow of refrigerant. The introducing passage may be located in the spiral wall of the movable scroll, or may be located in the movable scroll base plate. The preferred embodiment also includes a lubricant sump for collecting used lubricant in a lower pressure region of the compressor for re-introduction into a suction zone of the compressor via a lubricant passage interconnecting these two zones.